FORAGE YIELD AND QUALITY OF EARLY MAIZE HYBRIDS IN RESPONSE TO PLANTING DATE, NITROGEN AND PLANT DENSITY

Abstract

Management practices in corn (Zea mays L.) are important considerations for obtaining high yield production and good forage quality. In this study we evaluated the effect of planting date, nitrogen rates and plant density on forage yield and quality of two early corn hybrids, at Pabellón, Aguascalientes, México. The corn hybrids 'Halcón' and 'H-322E' were evaluated at two planting dates (May 6 and June 17, 2003), three plant densities (60, 80 and 100 thousands plants/ha) and two nitrogen rates (180 and 240 kg ha^-1). At 1/3 milk line stage we measured: total dry matter (TDM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and in vitro digestibility (IVD), and milk production per ton of dry matter (MT) and milk per hectare (MHA) were estimated. At the later planting date TDM, NDF and ADF were 2.4 t ha^-1, 25 g kg^-1 and 24 g kg^-1, respectively, and significantly higher than those obtained at the earlier planting date; however DIV, MT and MPH were similar at both planting dates. Nitrogen rate had no effect on forage yield and quality. As plant density increased from 60 000 to 100 00 plants/ha, TDM increased 4.5 t ha^-1 and MHA 1.9 t ha^-1, whereas IVD decreased 1.6 %. H-322E yielded 2.4 t ha^-1 more TDM than 'Halcón'; however, 'Halcón' had higher forage quality with higher DIV and MT, and lower NDF and ADF contents. The MHA of both hybrids was similar with a mean of 14.4 t ha^-1. Thus, with any of the two hybrids and any of the two planting dates, at a population density of 100 000 plants/ha and fertilized with 180 kg ha^-1 of nitrogen, it would produce high yield of milk per hectare at the Aguascalientes Valley.